Ultrasound echogenic cardiac lead

ABSTRACT

A lead has a flexible lead body which extends from a proximal end to a distal end. The lead body has a conductor coupled with an electrode. At least a portion of the conductor includes a layer of echogenic material encapsulated by the lead body. Alternatively, the echogenic material includes a coating of material. Optionally, the layer of echogenic material is disposed on at least a portion of the conductor or on one or more portions of the conductor.

TECHNICAL FIELD

The present invention relates generally to leads implanted in the heartand for conducting electrical signals to and from the heart. Moreparticularly, it pertains to an ultrasound echogenic cardiac lead.

TECHNICAL BACKGROUND

Leads implanted in or about the heart have been used to reverse certainlife threatening arrhythmias, or to stimulate contraction of the heart.Electrical energy is applied to the heart via the leads to return theheart to normal rhythm. Leads have also been used to sense in the atriumor ventricle of the heart and to deliver pacing pulses to the atrium orventricle.

Cardiac pacing may be performed by the transvenous method or by leadsimplanted directly onto the ventricular epicardium. Permanenttransvenous pacing is performed using a lead positioned within one ormore chambers of the heart. A lead may be positioned in the ventricle orin the atrium through a subclavian vein, or cephalic vein, and the leadterminal pins are attached to a pacemaker which is implantedsubcutaneously or submuscularly.

As the leads are implanted, or after the leads are implanted, the leadscan be monitored using fluoroscopy. However, some hospitals or otherplaces at which implantation of leads occurs have limited or no accessto fluoroscopic equipment, for instance in countries with limitedeconomic means. In addition, some patients should not be treated usingfluoroscopy, for instance, women in early stages of pregnancy.

Accordingly, there is a need for a lead which allows for monitoring ofthe lead during or after implantation of the lead. What is also neededis a lead which allows for monitoring of the lead without substantialrisk to the patient.

SUMMARY

A lead assembly is provided including a flexible lead body extendingfrom a proximal end to a distal end. The lead body has at least oneconductor and a layer of echogenic material disposed directly on or inthe conductor or directly on an inner surface of the conductor.Optionally, the conductor includes a helix forming an active fixationdevice disposed at the distal end of the lead body, where the echogenicmaterial is disposed on the helix.

The flexible lead body has an outer surface, where the layer ofechogenic material is completely encapsulated by the flexible lead body.An electrode assembly has at least one electrode which is electricallycoupled with the conductor. In one alternative, the lead assemblyincludes an inner layer of insulator, and the echogenic material isdisposed between the conductor and the inner layer of insulator. Inanother alternative, the conductor comprises one or more filars, eachfilar having an outer filar surface, the echogenic material disposeddirectly on at least a portion of the outer filar surface. In yetanother option, the echogenic material is disposed on one or moreportions of a length of the lead. Optionally, the echogenic materialcomprises an echogenic coating. The echogenic coating optionallycomprises a porous coating, a metallic coating, or a metal oxidecoating.

A lead assembly is provided including a flexible lead body extendingfrom a proximal end to a distal end. The lead body has at least oneconductor and a layer of echogenic material disposed directly on or inthe conductor. The conductor comprises one or more filars, each filarhaving an outer filar surface, the echogenic material disposed directlyon at least a portion of the outer filar surface. Optionally, theconductor includes a helix forming an active fixation device disposed atthe distal end of the lead body, where the echogenic material isdisposed on the helix.

The flexible lead body has an outer surface, where the layer ofechogenic material is completely encapsulated by the flexible lead body.An electrode assembly has at least one electrode which is electricallycoupled with the conductor.

In one alternative, the lead assembly includes an inner layer ofinsulator, and the echogenic material is disposed between the conductorand the inner layer of insulator. In yet another option, the echogenicmaterial is disposed on one or more portions of a length of the lead.

Optionally, the echogenic material comprises an echogenic coating. Theechogenic coating optionally comprises a porous coating, a metalliccoating, or a metal oxide coating.

A lead assembly is provided including a flexible lead body extendingfrom a proximal end to a distal end. The lead body has at least oneconductor and a layer of echogenic material disposed directly on or inthe conductor. The echogenic material is disposed on one or moreportions of a length of the lead.

Optionally, the conductor includes a helix forming an active fixationdevice disposed at the distal end of the lead body, where the echogenicmaterial is disposed on the helix.

The lead includes a layer of echogenic material which provides a costeffective alternative to monitoring an implanted medical device, such asa lead. The echogenic material also allows the lead to be monitoredsafely, without risk to patients having sensitive medical conditions. Inaddition, the layer of echogenic material is encapsulated by the leadbody, such that the exposed blood and tissue contact surfaces of thelead remain unaffected from long-term biocompatibility and biostability.

These and other embodiments, aspects, advantages, and features of thepresent invention will be set forth in part in the description whichfollows, and in part will become apparent to those skilled in the art byreference to the following description of the invention and referenceddrawings or by practice of the invention. The aspects, advantages, andfeatures of the invention are realized and attained by means of theinstrumentalities, procedures, and combinations particularly pointed outin the appended claims and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a system for monitoring and stimulating the heartconstructed in accordance with one embodiment.

FIG. 2 is a cross-section of a lead assembly constructed in accordancewith one embodiment.

FIG. 3 is a cross-section of a lead assembly constructed in accordancewith one embodiment.

FIG. 4 is a cross-section of a lead assembly constructed in accordancewith another embodiment.

FIG. 5 is a cross-section of a lead assembly constructed in accordancewith one embodiment.

FIG. 6 is a cross-section of a lead assembly constructed in accordancewith one embodiment.

FIG. 7 is a cross-section of a lead assembly constructed in accordancewith one embodiment.

FIG. 8 is a cross-section of a portion of a lead assembly constructed inaccordance with one embodiment.

DESCRIPTION OF THE EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and that structuralchanges may be made without departing from the scope of the presentinvention. Therefore, the following detailed description is not to betaken in a limiting sense, and the scope of the present invention isdefined by the appended claims and their equivalents.

FIG. 1 illustrates a single-pass lead 100 for delivering electricalpulses to stimulate a heart 101 and/or for receiving electrical pulsesto monitor the heart 101. The lead 100 extends from a distal end 102 toa proximal end 104, and has an intermediate portion 105 therebetween.The distal end 102 is adapted for implantation within the heart of apatient, the proximal end 104 has a terminal connector whichelectrically connects the various electrodes and conductors within thelead body to a pulse generator and signal sensor 109. The pulsegenerator and signal senor 109 contains electronics to sense variouselectrical signals of the heart and also produce current pulses fordelivery to the heart 101.

The lead 100 includes a lead body 115, an elongate conductor 116 (FIGS.2 and 3) contained within the lead body 115, and at least one electrode120 coupled with the lead 100. The at least one electrode 120 iselectrically coupled with the elongate conductor 116 (FIGS. 2 and 3).The lead body 115 is includes a biocompatible insulating material.Optionally, the elongate conductor 116 comprises a coiled conductor anddefines a lumen therein and thereby is adapted to receive a stiffeningstylet that extends through the length of the lead 100.

The stylet is used to stiffen the lead 100, and is manipulated tofacilitate the insertion of the lead 100 into and through a vein andthrough an intracardiac valve to advance the distal end 102 of the lead100 into, for example, the ventricle of the heart 101. A stylet knob iscoupled with the stylet for rotating the stylet, advancing the conductorinto tissue of the heart, and for manipulating the lead 100.Alternatively, the elongate conductor 116 comprises a cable conductor.

FIG. 2 illustrates a cross-section of the lead shown in FIG. 1,including the lead 100, and/or the lead 100 and the pulse generator andsignal sensor 109. The lead 100 is used to chronically stimulate theheart 101, such that the lead 100 is implanted on or about the heart 101for long periods of time. As mentioned above, the lead body 115 includesa covering of insulation. The lead 100 further includes a layer ofechogenic material 230, where the lead body 115 completely encapsulatesthe layer of echogenic material 230.

The layer of echogenic material 230 is disposed directly on or in theconductor 116. The conductor 116 is defined in part by an inner surface132 and an outer surface 134. As shown in FIG. 2, the layer of echogenicmaterial 230 is disposed directly on the outer surface 134 of theconductor 116. Alternatively, as shown in FIG. 3, the layer of echogenicmaterial 230 is disposed directly on the inner surface 132 of theconductor 116.

The layer of echogenic material 230 optionally extends the full lengthof the lead 100, from the proximal end 104 to the distal end 102 of thelead body 115. Alternatively, the layer of echogenic material 230extends for only a portion of the lead 100. In another option, asillustrated in FIG. 4, the echogenic is disposed on more than oneportion of the length of the lead, where multiple portions 232 ofechogenic material are disposed within the lead body 115. Optionally,the multiple portions 232 of echogenic material 230 are disposeddirectly on the conductor 116.

FIG. 5 illustrates another alternative of the lead 100. As mentionedabove, the lead body 115 includes a covering of insulation, and aconductor 116. The lead 100 further includes a second conductor 118, andan inner layer of insulation 114, where the inner layer of insulation114 surrounds the conductor 116, and the lead body 115 surrounds thesecond conductor 118. The inner layer of insulation 114 is disposedbetween the conductor 116 and the second conductor 118. The lead 100further includes a layer of echogenic material 230. The lead body 115completely encapsulates the layer of echogenic material 230, where thelayer of echogenic material 230 is disposed between the conductor 116and the second conductor 118. The layer of echogenic material 230 isoptionally disposed directly on the conductor 116. In another option,the layer of echogenic material 230 is disposed between the conductor116 and the inner layer of insulator 114, as shown in FIG. 6. The layerof echogenic material 230 optionally extends the full length of the lead100, from the proximal end 104 to the distal end 102 of the lead body115. Alternatively, the layer of echogenic material 230 extends for onlya portion of the lead 100, or is disposed on multiple portions, asdiscussed above.

FIG. 7 illustrates yet another option, where the lead 100 includes ahelix 254 forming an active fixation device. The layer of echogenicmaterial 230 is disposed on at least a portion of the helix 254.Optionally, the layer of echogenic material 230 is disposed at thedistal tip 256 of the helix 254. The echogenic material 230 also isoptionally disposed on two or more portions of a length of the lead 100.

The conductor 116 and/or the second conductor 118 are comprised of oneor more filars 290. As shown in FIG. 8, each filar 260 optionallyincludes a layer of echogenic material 270. It should be noted that thefilar 290 of FIG. 8 can be incorporated into any of the above describedleads, or leads not described herein.

The layer of echogenic material 230 comprises, in one option, anechogenic coating. The echogenic coating, for use with the abovediscussed embodiments, optionally comprises any one of the following: aporous coating, a metallic coating, or a metal oxide coating.Alternatively, the layer of echogenic material 230 is created by surfacetexturing. In yet another option, the layer of echogenic material 230 isformed by mixing additives into the lead body 115 or inner insulator,where the additives are of lower or higher density than the component inwhich the additive is mixed. Examples of additives include, but are notlimited to, metal powders, metal oxide powders, hollow glassmicrospheres, and various forms of carbon particles.

Advantageously, the above described lead provides a layer of echogenicmaterial which provides a cost effective alternative to monitoring animplanted medical device, such as a lead. The echogenic material alsoallows the lead to be monitored safely, without risk to patients havingsensitive medical conditions. Having the echogenic material disposeddirectly on the conductor allows for the location of the lead or medicaldevice to be monitored more accurately. In addition, the layer ofechogenic material is encapsulated by the lead body, such that theexposed blood and tissue contact surfaces of the lead remain unaffectedfrom long-term biocompatibility and biostability.

It is to be understood that the above description is intended to beillustrative, and not restrictive. It should be noted that features ofthe various above-described embodiments may be interchanged to formadditional combinations. Many other embodiments will be apparent tothose of skill in the art upon reviewing the above description. Forinstance, the layer of echogenic material as described above can beincorporated into a variety of medial devices and a variety of leads.The scope of the invention should, therefore, be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A lead assembly comprising: a flexible lead bodyextending from a proximal end to a distal end, the lead body includingat least one conductor disposed therein, the flexible lead bodyincluding an outer surface; a first layer of echogenic materialcompletely encapsulated by the flexible lead body; an electrode assemblyincluding at least one electrode electrically coupled with theconductor; the first layer of echogenic material is disposed directly onor in the conductor at a first location; and a second layer of echogenicmaterial disposed directly on or in the conductor at a second location.2. The lead assembly as recited in claim 1, wherein the first layer ofechogenic material comprises an echogenic coating.
 3. The lead assemblyas recited in claim 2, wherein the echogenic coating comprises a porouscoating.
 4. The lead assembly as recited in claim 2, wherein theechogenic coating comprises a metallic coating.
 5. The lead assembly asrecited in claim 2, wherein the echogenic coating comprises a metaloxide coating.
 6. The lead assembly as recited in claim 1, wherein theconductor is a coiled conductor coil having an inner surface, and thefirst layer of echogenic layer is disposed within the conductor directlyon the inner surface.
 7. The lead assembly as recited in claim 1,further comprising an inner layer of insulator, and the first layer ofechogenic material is disposed between the conductor and the inner layerof insulator.
 8. The lead assembly as recited in claim 1, wherein theconductor comprises one or more filars, each filar having an outer filarsurface, the first layer of echogenic material disposed directly on atleast a portion of the outer filar surface.
 9. The lead assembly asrecited in claim 1, wherein echogenic material is disposed on three ormore portions of a length of the lead.
 10. The lead assembly as recitedin claim 1, wherein the conductor includes a helix forming an activefixation device disposed at the distal end of the lead body, wherein thesecond layer of echogenic material is disposed on the helix.
 11. A leadassembly comprising: a flexible lead body extending from a proximal endto a distal end, the lead body including at least one conductor disposedtherein, the flexible lead body including an outer surface; a firstlayer of echogenic material disposed within the outer surface of thelead body; and an electrode assembly including at least one electrodeelectrically coupled with the conductor; wherein the conductor comprisesone or more filars, each filar having an outer filar surface, the firstlayer of echogenic material disposed directly on at least a portion ofthe outer filar surface at a first location; and a second layer ofechogenic material disposed directly on or in the conductor at a secondlocation that is different than the first location.
 12. The leadassembly as recited in claim 11, wherein the first layer of echogenicmaterial comprises an echogenic coating.
 13. The lead assembly asrecited in claim 12, wherein the echogenic coating comprises a porouscoating.
 14. The lead assembly as recited in claim 12, wherein theechogenic coating comprises a metallic coating.
 15. The lead assembly asrecited in claim 12, wherein the echogenic coating comprises a metaloxide coating.
 16. The lead assembly as recited in claim 11, furthercomprising an inner layer of insulator, and the first layer of echogenicmaterial is disposed between the conductor and the inner layer ofinsulator.
 17. The lead assembly as recited in claim 11, wherein thefirst and second layer of echogenic material extend from the proximalend to the distal end of the lead body.
 18. The lead assembly as recitedin claim 11, wherein the echogenic material is disposed on three or moreportions of a length of the lead.
 19. The lead assembly as recited inclaim 11, wherein the conductor includes a helix forming an activefixation device disposed at the distal end of the lead body, wherein thefirst layer of echogenic material is disposed on at least a portion ofthe helix.
 20. A lead assembly comprising: a flexible lead bodyextending from a proximal end to a distal end, the lead body includingat least one conductor disposed therein, the conductor including aconductor outer surface; a layer of echogenic material disposed on atleast a portion of the conductor outer surface, wherein the echogenicmaterial is disposed on two or more portions of a length of the lead;and an electrode assembly including at least one electrode electricallycoupled with the conductor.
 21. The lead assembly as recited in claim20, wherein the conductor includes a helix forming an active fixationdevice disposed at the distal end of the lead body, wherein theechogenic material is disposed on the helix.